Stabilizers are used in modern motor vehicles in order to improve roll stability and consequently road position, in particular on bends. The stabilizer is, in this instance, arranged between wheels of an axle (front or rear axle), and connects of the wheels via levers and a torsion bar. The resilient action is achieved by rotation (torsion) of often round torsion bars. A central portion of the stabilizer, which forms the torsion bar, is rotatably arranged on bodywork, wherein angled ends that act as levers are fitted to elements of a wheel suspension, normally via vertically extending coupling rods. If one wheel is raised relative to the other, for example, in an event of single-sided loading on a bend, this brings about a torsion of the stabilizer, or the central portion. As a result of a resultant force, an opposing wheel is also raised, whereby an oblique position of the bodywork is limited.
In particular with off-road vehicles and SUVs, an extreme, one-sided deflection of a wheel may occur, particularly when the vehicle is used in an off-road sector. A significant deflection places, on the one hand, high demands on springs and shock-absorbers, but, on the other hand, also on the stabilizer. There is a significant torsion of the torsion rod that, when occurring repeatedly, may lead to material fatigue. This material fatigue may impair resilience of the stabilizer, or in the worst case even lead to the stabilizer breaking.
In principle, this danger may be overcome by the suspension being constructed to be more rigid so that spring excursion is reduced. Where applicable, however, this has an undesirable effect on an overall behavior of the suspension. It is also possible to limit the spring excursion via stop dampers that inevitably impairs even-sided redirection. It is further possible to construct the stabilizer in a more stable manner, whereby the stabilizer does, however, react in a more rigid manner, that is to say, even with slight, single-sided deflection. Furthermore, the stabilizer thereby becomes generally heavier.
US 2010/0090432 A1 discloses a coupling element for connecting a stabilizer to a transverse link. A cylinder portion of the coupling element is connected to the stabilizer, and a piston portion is connected to the transverse link. In this instance, a portion of the piston portion is arranged in a telescope-like manner in a recess of the cylinder portion. An inner wall of the cylinder portion has a groove in which locking elements can engage at a side of the piston portion. By an actuator and a mechanism that is arranged therebetween, locking elements can be adjusted in order to lock the cylinder portion and the piston portion with respect to each other, or to release them from each other. The latter leads to decoupling of the stabilizer from the wheel suspension that is intended to be carried out automatically during cross-country travel at a request of the driver.
A similar arrangement is set out in U.S. Pat. No. 6,659,475 B2, wherein a groove is provided in an outer wall of a piston portion, and wherein locking elements are arranged at a side of a cylinder portion, and, by an actuator, can be moved inward out of an inner wall of the cylinder portion. A decoupling may in this instance be actuated by a control unit that evaluates signals of sensors that, for example, measure a movement of transverse links.
Another concept for decoupling a stabilizer is known from U.S. Pat. No. 6,637,757 B2. In this instance, a torsion rod of a stabilizer is constructed in two halves, which are connected to each other by a coupling. The coupling may be released by an actuator, which in turn is controlled by a control unit. Similar concepts are known from U.S. Pat. No. 6,481,732 B1 and U.S. Pat. No. 6,425,585 B1. US 2016/089951 A1 also sets out a comparable concept, wherein furthermore stabilizer arms are connected to a respective wheel suspension by coupling elements. These coupling elements are not rigid, but instead comprise two portions that can be displaced slightly with respect to each other in a longitudinal direction, wherein two resilient elements that absorb tensile or pressure forces are interposed.
U.S. Pat. No. 5,186,486 A sets out a stabilizer arrangement for a motor vehicle in which at least one arm of a stabilizer is connected to a wheel suspension by an active connection arrangement. A housing portion of the connection arrangement is connected to the wheel suspension, whilst a rod element that is partially arranged in the housing is connected to the stabilizer arm. The rod element, which has a toothed rod at one side, is guided between a guiding roller and a toothed wheel. The toothed wheel can be controlled by a drive, wherein three operating modes are possible. A stopper element can be completely locked with respect to the housing, the stopper element may be freely movable, or an active adjustment of the rod element is carried out via the drive, whereby a stabilizer force is actively controlled.
U.S. Pat. No. 5,505,480 A discloses a stabilizer arrangement in which a stabilizer arm is connected by a coupling element to a wheel suspension. The coupling element has a cylinder and a resiliently loaded piston, which is arranged therein. The cylinder is filled with a hydraulic fluid, which can be replaced via a compensation line between an upper cylinder portion and a lower cylinder portion. If a gear mechanism of the vehicle is in a higher gear, the compensation line is blocked by an actuator, whereby the piston is hydraulically locked with respect to the cylinder. If the gear mechanism is in a low gear, the compensation line is opened so that the piston can be moved with respect to the cylinder.
In view of the prior art set out, protection of a stabilizer from overload still leaves room for improvement.